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 A127075 a(1)=1. a(n) = a(n-1) + (sum of the earlier terms {among terms a(1) through a(n-1)} which are coprime to n). 2
 1, 2, 5, 11, 25, 67, 178, 287, 863, 2092, 5612, 6871, 22885, 53613, 69597, 223822, 385931, 802877, 2308019, 5936156, 12937623, 29456690, 81587807, 166703456, 437728341, 973247233, 2233938123, 4919445412, 13784085189, 14842425156 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Robert Israel, Table of n, a(n) for n = 1..3121 EXAMPLE The terms of the sequence, among terms a(1) through a(5), which are coprime to 6 are a(1)=1, a(3)=5, a(4)=11 and a(5)=25. So a(6) = a(5) +1 +5 +11 +25 = 67. MAPLE A[1]:= 1: for n from 2 to 100 do A[n]:= A[n-1]+convert(select(t -> igcd(t, n)=1, [seq(A[i], i=1..n-1)]), `+`) od: seq(A[i], i=1..100); # Robert Israel, Aug 23 2019 MATHEMATICA f[l_List] := Append[l, l[[ -1]] + Plus @@ Select[l, GCD[ #, Length[l] + 1] == 1 &]]; Nest[f, {1}, 30] (* Ray Chandler, Jan 06 2007 *) CROSSREFS Cf. A127076. Sequence in context: A226974 A047775 A001432 * A053429 A266879 A104237 Adjacent sequences: A127072 A127073 A127074 * A127076 A127077 A127078 KEYWORD nonn AUTHOR Leroy Quet, Jan 04 2007 EXTENSIONS Extended by Ray Chandler, Jan 06 2007 STATUS approved

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Last modified May 28 18:29 EDT 2023. Contains 363019 sequences. (Running on oeis4.)